TL082 Adjusticator - input output put what where?

Started by Noplasticrobots, March 20, 2006, 06:45:41 PM

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Noplasticrobots

I'm having a bit of trouble understanding how to wire up the two stages of the Adjusticator (putting them in series) using a TL082.

Actually, I'm having a bit of trouble as to what exactly the Adjusticator is! I was suggested to build it as a preamp and I like the way it sounds, but it seems that you're supposed to use it between effects to keep wild ones tamed.

Anyway, on to my questions...

If I use two Adjusticators in series, does this mean I use a total of four jacks and two pots? Or Do I keep my input on U1A and move the output to U1B with all resulting circuitry in between using only two jacks and two pots? And speaking of circuitry, how exactly do I hook up both op amps? I know I need to take the output from U1A and connect it to the non inverting input of U1B, but do I need the 2.2M resistor and 10uf cap between them?

I'm thoroughly confused.
What it comes down to is that I need to connect two Adjusticators in series using one TL082 dual op amp.  :P

Here's the schematic:

http://www.geofex.com/circuits/Adjusticator.gif

I greatly appreciate any help anyone can provide.

I love the smell of solder in the morning.

calpolyengineer

If you want them connected in series all the time, then you only need two jacks and two pots. The output of one adjusticator goes straight into the input of the other and you can eliminate the 2.2M resistor on the input of the second one.

However, it seems like it could be very convenient to have two adjusticators which can be run in series or in completely separate places in the signal chain. For this, you would need 4 jacks and 2 pots. Then if you wanted to run them in series you would only need a small patch cord from the output of one to the input of the other, or you could use a switching jack so that the output of the first one is automatically routed to the input of the second unless a plug is in the output.

-Joe

R.G.

QuoteActually, I'm having a bit of trouble as to what exactly the Adjusticator is!
The Adjusticator is an inverting opamp stage with an adjustable gain, ranging from 1/10th to 20, or -20db to +20db ( approximately).

The schematic shows two of them. The idea is that you can use two of them to adjust signal levels to most things you need the signal adjusted upon. In this use, the first one sets the signal level going TO whatever effect you drive, and the second one adjusts the level of what comes back.

QuoteIf I use two Adjusticators in series, does this mean I use a total of four jacks and two pots?
It depends on what you're trying to do. If you're just using it as a preamp, hook up the two sections together; this uses two jacks. If you're using it to adjust levels going to some external device, the external device has to get hooked in between the two, and that requires four jacks. You can hardwire the pots values if you're sure you'll never change them.

QuoteOr Do I keep my input on U1A and move the output to U1B with all resulting circuitry in between using only two jacks and two pots?
For just preamp work, yes, that's fine.

QuoteAnd speaking of circuitry, how exactly do I hook up both op amps? I know I need to take the output from U1A and connect it to the non inverting input of U1B, but do I need the 2.2M resistor and 10uf cap between them?
You could:
- leave all the circuitry there, just connect the middle "out" to the middle "in".
-  Hook the middle out to the middle in, removing either one or both 2.2M resistors.
- Ditto, but leaving out the 10uF cap.
- it actually oughta work if you remove the 10uF, the 0.1uF, and both 2.2M resistors and hook the second section 100K directly to the output of the first opamp. This may get you some DC offset, through.
QuoteI'm thoroughly confused.
What it comes down to is that I need to connect two Adjusticators in series using one TL082 dual op amp.
Just build one one each side of the TL082, then connect  them up as noted.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

Noplasticrobots

R.G. you are a gentelman and a scholar. As soon as I wake up tomorrow I'l be finishing this circuit. Thanks for throwing me a life preserver!
I love the smell of solder in the morning.

Noplasticrobots

R.G. you are a gentelman and a scholar. As soon as I wake up tomorrow I'l be finishing this circuit. Thanks for throwing me a life preserver!
I love the smell of solder in the morning.